I can factually attest to the fact that foliage on trees will attenuate RF.
I can't hear signals off of the moon on 432 when it is below the top of the
pine tree just a few yards from my array to the east.
Also, a significant amount of RF can ignite a tree. I lit the top of a
maple during a Fall EME contest. The leaves were quite dry and I let the
high gain array, fed with lot of power, skew down such that the tree was
into the major lobe of the antenna. Quite impressive site. The tree
suffered little damage.
As to HF signals, trees will little effect on signals. However, the wire
contacting the tree may cause the tuning to change with changing moisture
levels due to season of the year or precipitation.
Your mileage may vary.
73
Bob, K4TAX
----- Original Message -----
From: "Rob Atkinson K5UJ" <k5uj@hotmail.com>
To: <tentec@contesting.com>
Sent: Saturday, February 04, 2006 7:51 AM
Subject: [TenTec] re Trees
> The topic of trees has come up elsewhere (towertalk and a broadcast
> reflector i read) and i can say from reading them that the consensus is
> that
> trees attenuate RF if they are in the near field. this is why mw and sw
> broadcasters clear trees off their sites but, it isn't always such a big
> problem that you should abandon the idea of putting your vertical dipole
> amongst them. I would be more concerned about pine tree contact with the
> high v. end of ur dipole and burning. Have not experienced this myself
> (and being a chicken i hired a guy to trim a pine tree away from part of
> my
> loop) and nothing may happen in your case, but if i were you and i ran
> QRO,
> i'd rest easier if I could position the wire so that it's a few feet from
> any branches and needles, or if that isn't possible, trim anything making
> contact back a few feet. Some guys say they get around this by using
> insulated wire, but I have also read that the insulation can rub off
> eventually.
>
> rob / k5uj
>
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